Puzzled by Voltage. why does 120 volts need a neutral but not 220 volts.?

Question

Puzzled by Voltage. why does 120 volts need a neutral but not 220 volts.?

Answer 1

They both need a neutral, 120 is one hot and 220 is 2 hot wires. What makes you think 220 doesn't need a neutral?

Answer 2

Let's see if I can help with the concept.

Alternating current (ac) is "push-pull". The electrons go in one direction for half the cycle and back during the other half. In the case of 220 volts the two lines are 180 degrees out of phase, exactly opposite. So as one line is pushing at 120 volts the other line is pulling at 120 volts and that gives you the 240 volts difference. (It will be 110v and 220v or 120 volts and 240v or something in between but the latter will be double the former).

To use the water and hose analogy. With 120volts you have a 120 volt "pump" at one end of a hose and tub of water at the other end (the neutral) Then you would be pushing water in to the tub during half the cycle and pulling out it during the other half.

With 240v you have a pump on both ends. So while you are pushing on one end somebody else pulling the water out at the other. Then you are just pushing and pulling the same water back and forth in the hose. In that case you don't need the tub of water which is your "neutral".

I hope that helps.  

Answer 3

A neutral is a grounded current carrying conductor and it would work if it was not grounded.  

However the standard in a home is to ground one leg of the 120volt system.  This makes it so you only have to switch the hot leg since the other leg is neutral. It's also safer and easier to troubleshoot.

Some factories run 120 volts on machinery without grounding one leg, then they have to open both legs when turning things on and off.

Answer 4

The 2 voltages each need a return line to operate properly. In the case of 240 volts the power is from one line to the other, in the 120 volts the neutral is 1/2 of the power.  Think of a water hose, in a "S" bend with a connection in the middle. With the middle connection open, you have 120, with it closed and the two ends open, you have 240. Hope this helps, it's not accurate but will help as a concept.  

Answer 5

You assume too much- 220 is just a pair of 110's with a common neutral. A.c. electric at these voltages always includes a neutral otherwise it would be described as death waiting to happen.